* Fed ties policy to specific economic target
* Fed extends debt-buying in line with expectations
* Speaker of the U.S. House Boehner again rejects Obama's demand
* Yen down across the board on prospects of more easing
By Julie Haviv
NEW YORK, Dec 13 (Reuters) - The dollar held steady against the euro after falling for three straight days on Thursday as a looming U.S. fiscal crisis curbed...